Conversion arthroplasty of the hip: mid-term results are good.

The historical mid-term results of conversion total hip arthroplasty (THA) are acceptable; however, the complication rates are high. In total, 39 patients (45 hips) from 2 institutions underwent conversion THA from 1993-2006 and were retrospectively evaluated. The mean age was 48.3 years, the mean follow-up time was 8.7 years, and the mean duration arthrodesis prior to conversion THA was 18.2 years. The outcomes included operative time, blood loss, leg-length discrepancy (LLD), thigh circumference, Harris Hip Score (HHS), complications, and radiographic evaluation. A total of 34 THAs were cemented, and 11 were uncemented. The mean operative time was 102 minutes, and the mean blood loss was 1019 ml. The mean HHS improved from 32.4 to 82.5 (p<0.01). The mean LLD decreased from 4.2 to 1.1 cm, while the thigh circumference increased by a mean of 1.6 cm. Complications included: a positive Trendelenburg gait (6), early haematoma that required surgical evacuation (5), dislocation (2), deep infection (1), and early aseptic loosening of the components (2). In conclusion, the functional results of the conversion THA using predominantly cemented components are good at mid-term follow-up; although the complication rates remain higher than a standard primary THA, aseptic loosening rates of the cemented components is low at mid-term follow-up.